The invention is in the field of calculators employing dynamic storage of information and dynamic display of stored information, and specifically relates to calculators of this type in which the rate of power consumption is of concern, such as in hand-held calculators which are battery powered.
Calculators of this type typically have three alternate operating modes. There is an execute mode during which input information is decoded and is arithmetically and logically processed in accordance with either input or stored commands to provide selected processed information. The execute mode operation is typically followed automatically, without operator intervention, by a display mode in which selected processed information is displayed. When selected new information is entered, there is a new execute mode operation followed by a new display mode operation. If there is no new execute mode operation within a certain time interval, the calculator automatically goes into a display inhibit mode (alternately called blanking), in which the relevant information is no longer displayed, but is maintained in storage so that it can be again displayed if needed.
A typical calculator of this type (disclosed in White et al. U.S. Pat. No. 3,781,852) operates at full power during all three modes of operation, the only power reducing scheme being that the display is not driven during the display inhibit mode of operation. A somewhat different approach is disclosed in Bogert et al. U.S. Pat. No. 3,453,601 where a calculator is clocked at a high frequency during its arithmetic mode operation to ensure high calculating speed but is clocked at a lower frequency and low duty cycle during its subsequent display mode operation in order to reduce power consumption. However, the Bogert et al. system has no display inhibit mode of operation and has no special provisions for applying power to the calculator at different duty cycles during different modes of operation.